1. Field
Example embodiments are directed to image sensors, for example, to image sensors that may improve signal saturation and sensitivity by improving a fill factor, and methods of fabricating the image sensors.
2. Description of Related Art
An image sensor may convert an optical image into an electrical signal. A Metal-Oxide Semiconductor (MOS) image sensor may be implemented using various scanning methods. Because a MOS image sensor may be integrated into a single chip, the miniaturization of products incorporating image sensors may be facilitated. Because existing MOS manufacturing technology may be used to manufacture MOS image sensors, manufacturing costs associated with the image sensors may be decreased. Further, because power consumption by the image sensors may be relatively low, MOS image sensors may be more readily applied to products having a limited battery capacity.
However, as the integration of pixels increases in order to satisfy increased resolution, the size of each pixel may decrease, thereby decreasing the fill factor as well. The term “fill factor,” as used herein, may refer to the ratio of the area of a photoelectric transformation element to the area of a unit pixel.
Because a photoelectric transformation element and read gates, for example, a select element, a drive element and a reset element, may need to be spaced apart from each other, there is a limitation in the increase in the volume of a photoelectric transformation element due to this design trade-off for the read gates and the photoelectric transformation element.
Since the volume of a photoelectric transformation element per unit pixel may be decreased, signal saturation and sensitivity may deteriorate.